Inductance device



H. J, POWER. "INDUCTANCE, DEVICE. APPLICATION FILED MAR-11,1918.

Patented Sept. 19, W22.

Patented Sept. 19, 1922.

UNITED STATES 1,429,453 PATENT OFFICE.

HAROLD J. POWER, OF SOMERVILLE, MASSACHUSETTS, ASSIGNOR TO AMERICAN RADIO & RESEARCH CORPORATION, OF MEDFORD, MASSACHUSETTS, A CORPO- RATION OF DELAWARE.

INDUCTANCE DEVICE.

Application filed March 11,

tion.

In certain electrical current-carrying instrumentalities of which inductance devices furnish an example, and especially those employed in connection with such high frequency currents as are present in wireless or radio installations, it is important to prevent the loss of energy from the conductors through their insulating supports, and to so compactly arrange the devices that little space is occupied and,- further, so that two or more of the devices may be brou ht into close relation to produce a mutua edect. These results are obtained by the present invention, which is here disclosed as embodied in an inductance spiral for radio work, though obviously its novel features may be otherwise utilized.

In the accompanying drawing,

Fig. 1 is a top plan View of an inductance device arranged in accordance with my invention, and F ig. 2 is an enlarged vertical section on the line 22 of Fig.

At 10 and 11 are shown inner and outer supporting members of any suitable insulating material. As illustrated, these members are in the form of rings of rectangular cross section, they being concentrically arranged and having through their walls, midway between the upper and lower sides, radial openings 12 which are preferably equally spaced about the rings and which may be brought into alinement. Between the rings, enclosed in the narrow supporting and protecting frame furnished thereby, is a conductor 13, in the present instance consisting of a spiral ribbon extending in regular, uniformly separated convolutions from its inner extremity let to the outer end 15 to forfn a flat pancake type of spiral, at which points 14 and 15 connection may be made to the external circuit. Between the ,edges of the ribbon, preferably midway, areopenings 16 alined with one another radiallv and with corresponding openings 12 in-the insulating rings 10 and 11, the radial series 1918. Serial I10. 221,641.

of openings being here shown as separated by angles of 30. Through the openings 12 and 16 extend carrier members furnished by rods 17 of insulating material, which may be retained in place by the engagement of the edges of the openings 16 in the spiral. Mounted upon the rods between the convolutions of the conductor are insulating separating members 18, conveniently in the form of thimbles surrounding the rods, there being one of these members 18 between each of the adjacent pairs of convolutions of the spiral andalso between the inner and outer turns and the insulating rings. These thimbles space the turns of the spiral to keep them out of contact with one another and to maintain them in symmetrical relation. The parts of the device may readily be assembled by inserting the rods 17 through the openings, successively bringing the thimbles into position between the convolutions of the spiral so that the rods will pass through them. If desired, the thimbles may be cemented to the rods by means of an in sulating varnish, this also excluding air and tending to produce a uniform supporting dielectric.

It will be obvious that the entire device, including both the conductor and its insulating supports In comprised in a narrow space,

- so that itftakes up little room in the contracted quarters commonly provided for radio apparatus: and that, moreover, a plurality of these devices may be placed with their rings one above the other, with the planes of the spirals parallel and in close proximity. This produces in a most effective manner, both as to distance and relation, a mutual inductive action to aid self inductance in producing the desired total inductance. l/Vith high radio frequencies the current in the conductor of the form illustrated flows almost wholly at the edges of the ribbon. Consequently the supporting dielectric, which at best may be of imperfect insulating properties, is in contact with the conductor at points outside the current path so that the loss by leakage is small, and the portion of the conductor outside the openings 16, which carries the current, is uniorm in cross section and in resistance. Moreover, the separation between the current path and the supporting dielectric tends to minimize the loss of energy through 

